CVE-2021-29726Network attack vector

Host impersonation via improper certificate validation

Published May 17, 2022 · Updated Sep 16, 2024

Improper certificate validation in IBM Sterling products 6.0.3 allows remote attackers to impersonate trusted hosts during TLS connections. The TLS certificate-validation path accepts a certificate without confirming that its identity matches the host being contacted. Exploitation requires influence over the connection path and can redirect trust to an unintended peer without granting local code execution.

CVSS severity5.3
Medium
EPSS probability0.87%
Next 30 days · Sep 17, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper certificate validation in IBM Sterling products 6.0.3 allows remote attackers to impersonate trusted hosts during TLS connections. The TLS certificate-validation path accepts a certificate without confirming that its identity matches the host being contacted. Exploitation requires influence over the connection path and can redirect trust to an unintended peer without granting local code execution.

The record

CVE
CVE-2021-29726
Published
May 17, 2022
Updated
Sep 16, 2024
Vendor
IBM
Product
IBM Sterling Secure Proxy
Classifications
CWE-295, T1557
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 17, 2022CVE publishedPublication date reported by the CVE source.
  2. Sep 16, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=6.0.3

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

IBM · IBM Sterling Secure Proxyversion=6.0.3
IBM · IBM Sterling External Authentication Serverversion=6.0.3

Published CVSS scores

5.3IBM CorporationCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
5.3National Vulnerability DatabaseCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-295Improper Certificate Validation
T1557Adversary-in-the-Middle

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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